This invention relates to a machine for packaging with single-folded heat-shrinkable film which is characteristically provided with an air device able to force apart those opposing sides of the film between which the product to be packaged is to be inserted. The expert of the art is familiar with packaging machines which use single-folded heat-shrinkable film, i.e. film folded longitudinally to define two opposing faces which when forced apart define a space into which the product to be packaged is inserted.
The product is fed, inserted between the film faces, to a welding machine which welds the open sides of the film to form a closed envelope. This envelope is then fed into a hot air circulation oven which shrinks the film onto the product, to form the finished package.
A packaging machine of this type is described and illustrated for example in U.S. Pat. No. 4,104,848 granted Aug. 8, 1978, to which reference should be made for further details.
The packaging machine of the cited patent welds and heat-shrinks the film in a single chamber, through which hot air is circulated. The chamber is closed upperly by a preferably transparent movable hood, and the product to be packaged is inserted between the faces of the single-folded film sideways to the hood where a work table is positioned between said film faces.
To place the product to be packaged onto the work table the upper face of the single-folded film has to be raised manually, resulting in a time wastage which can be considerable in that these manual packaging machines are inherently rather slow compared with automatic tunnel machines.
A further drawback of machines of known type is that the film has to be perforated so that the air which was incorporated on inserting the article to be packaged between the two film faces can escape during the heat-shrinkage operation.
Consequently a package is obtained comprising holes which besides detracting from its appearance allow air to enter, this being undesirable particularly in the food field.